Cylindrical Microwave Oven

ABSTRACT

A cylindrical microwave oven comprises a shell ( 1 ) an oven cavity ( 2 ) and a microwave generator ( 3 ) inside the shell radiating microwave into the cavity. A door ( 6 ) for closing or opening the cavity ( 2 ) is mounted in the front of the shell. An upper disk cover ( 21 ), a U-shaped board ( 22 ) and a lower disk cover ( 23 ) form a cavity ( 2 ) with a front opening ( 101 ). The U-shaped board is supported between the upper cover ( 21 ) and the lower cover ( 23 ). The door ( 6 ) is a circular arc board for closing or opening the front opening ( 101 ) of the cavity ( 2 ).

FIELD OF THE INVENTION

The present invention relates to a microwave oven, concretely to a cylindrical microwave oven.

BACKGROUND OF THE INVENTION

Conventional microwave ovens have an oven cavity and a microwave generator radiating microwave into the cavity inside the shell; a rotating tray arranged inside the oven cavity; an electric motor driving the rotating tray mounted under the oven cavity of the shell, and its shaft connected to the rotating tray in the oven cavity; a door for closing or opening the cavity is mounted in the front of the shell; the sectional shape of the cavity is a square or a rectangle, and the radius of gyration is the width of the shortest border, thus the space of the four corners of the cavity is not used effectively. The door is hinged connected to the front of the shell, when opened, it rotates to the front and one side of the shell, thus it occupies the outer space.

SUMMARY OF THE INVENTION

The primary object of the present invention is to provide a cylindrical microwave oven with a high utilization ratio of the oven cavity and a less occupation space.

The object of the present invention is achieved by providing a cylindrical microwave oven with an oven cavity and a microwave generator radiating microwave into the cavity inside the shell; a door for closing or opening the cavity is mounted in the front of the shell. An upper disk cover, a U-shaped board and a lower disk cover form a cavity with a front opening. The U-shaped board is supported between the upper cover and the lower cover. The door is formed of a pair of circular arc boards for closing or opening the front opening of the cavity.

The said door comprises two door boards opposite-opened along a round way, and an opening mechanism for controlling the opening and closing of the two door boards mounted on the shell. The two door boards sliding on the round slide way, thus the opening and the closing will not occupy the outer space. Half of the inside space of the cavity will be exposed when the door boards opened, this has smaller amplitude of operation and more exposed inside-space compared with the single-door structure, so it is convenient to input or output the food. And the opening mechanism makes the opening of the door boards more simply and conveniently.

The said opening mechanism comprises two long rods, two short rods and a guide board; the two long rods are V-shape hinged and their hinged axis is hinged to one terminal of the guide plate; the free ends of the two long rods are fixed on the lower portion of the two door boards respectively; the two short rods are V-shape hinged and their hinged axis is connected slideably to the other terminal of the guide board; the free ends of the two short rods are hinged to the middle portion of the two long rods respectively; the guide board fixed on the shell. This mechanism can ensure the synchronous-opening, same opening-degree and good-seal of the two door boards.

The butt sides of the two door boards mounted hook mechanisms, the preferred art is to mount two hook mechanisms on the upper part and lower part of the butt sides of the two door boards respectively. When the door boards are closed, the hook mechanisms will ensure them not opened casually to prevent the microwave from leaking out.

One assembly art is to position the microwave generator on the upper cover and position the electric motor under the lower cover.

The upper portion of the cavity inside the said shell has a round upper slide way which used for the sliding and limiting of the door boards, The lower portion of the cavity inside the said shell had a bottom plate for supporting the cavity, and on the bottom plate there is a round lower slide way which used for the sliding and limiting of the door boards; an electric motor mounted on the bottom plate. The door boards slides between the upper slide way and the lower slide way, and they are position-limited to benefit to seal.

The upper side of the said door boards have an upper pulley connected to the upper slide way. The lower side of the said door boards have a lower pulley connected to the lower slide way. The resistance of the opening or the closing is small.

The cavity of the cylindrical microwave oven of the present invention is cylindrical, and the radius of gyration of the rotating tray is used as the cylinder diameter, thus it is not only making the best of the space, but also benefit to the radiating distribute of the microwave, which saves the heating time of the microwave acting on the food and improve the efficiency. It uses the opposite-opened circular arc door boards, after opened, the door boards opened at the opposite forward at the same time and sliding on the circle slide way, this saves the outer space needed in the hinged opening door boards. When the door boards are opened, half of the cavity will be exposed, which is convenient to input and output of the vessel and to clean the cavity. The opening mechanism is a four-link structure having two opposite-opened V-shape, this can ensure the synchronous opening, same opening degrees and good seal effect of the two door boards. The butt sides of the two door boards mounted hook mechanisms, after the door boards closed, the hook mechanisms will ensure them not opened casually to prevent the microwave from leaking out. The upper side of the said door boards have an upper pulley connected to the upper slide way. The lower side of the said door boards have a lower pulley connected to the lower slide way. The resistance of the opening or the closing is small, and can ensure the uniformity of the interstice between the door boards and the shell to prevent microwave from leakage out. Adding the electric motor and simply drive mechanism achieves the object of auto-opening and auto-closing.

Another art of the present invention is to provide a cylindrical microwave oven whose opening mechanism can perform the function of auto-opening and auto-closing of the two door boards.

Aforementioned opening mechanism of the cylindrical oven can switch between the manual operation or auto operation so as to open or close the two door boards.

The detailed art of the present invention is that: An opening mechanism of the cylindrical microwave oven, herein the two door boards opposite-opened along the slide way inside the shell of the microwave oven can seal the front opening of the cylindrical cavity, the gyration center of the door boards has a rotating shaft which V-shaped hinged with two rods; The free ends of the two rods fixed on the same side door boards respectively; one concentric circle of the said gyration center arranged two up-down staggered and fan out circular arc racks, each fan out terminals of the two said racks connected to a said rod respectively; each side of the symmetric line of the fan out racks mounted a gear respectively, the said gears mesh each other and each mesh to one rack respectively, one of the gears connected to the electric motor. The electric motor drives the racks via their meshed gears to let the racks fan out or closed relative to the symmetric line, the rod connected to the fan out terminal of the rack drive its connected door move towards the opening or closing forward along the circle slide way; the gear drive the other gear rotate reversely, then the other gear will drive the meshed rack fan out opened or closed relative to the symmetric line; the rod connected to the fan out terminal of the rack drive the connected door move towards the opening or closing forward along the circle slide way; thus achieved that the door boards auto-opening or auto-closing along the circular slide way.

The switching of manual operation or auto operation so as to open or close the two door boards of the present invention is achieved by that: a driving gear mounted on the rotating shaft of the said electric motor; the rotating shafts of the two gears mounted on a translation component; when the translation component is on the first position, the driving gear will mesh the said first gear; when the translation component moved to the second position, the driving gear will deviate from the first gear.

A preferred structure of the translation component is that: the said translation component is a U-shaped slice mounted on the tooth side of the two racks, each of the two opening plate parts of the U-shaped slice has two holes for mounting the rotating shaft of the two gears respectively; when the U-shaped slice is on the first position, the two gears will mesh their corresponding rack and the driving gear mesh the first gear; when the U-shaped slice is on the second position where is far from the tooth side of the two racks, the two gears will deviate from their corresponding rack and the driving gear deviate from the first gear.

In one preferred embodiment, the said U-shaped slice inserted in a guide box on the shell of the microwave oven; each of the two plate parts of the U-shaped slice has a long guide hole respectively, the upper and lower surfaces of the guide box have a embossed strip inserted in the corresponding long guide hole of the U-shaped slice respectively; the guide box has an upper and a lower staggered arc grooves for containing the two racks, the two said gears are mounted in the rack guide box respectively, herein the first gear has a coaxial smaller gear; when the U-shaped slice is on the first position, the embossed strips of the top and bottom surfaces of the guide box will be in the terminal having corresponding long guide hole of the U-shaped slice, the two gears will mesh their corresponding racks and the driving gear of the electric motor will mesh the small gear of the first gear; When the U-shaped slice is on the second position, the embossed strips of the top and bottom surfaces of the guide box will be in the other terminal having corresponding long guide hole of the U-shaped slice, the two gears will deviate from their corresponding racks and the driving gear of the electric motor will deviate from the small gear of the first gear.

Furthermore, it using a cam to achieve the U-shaped slice moving from the first position to the second position, i.e. the switching from auto-operation to manual operation; the top and bottom surfaces of the said guide box has a lug extending out from the tooth side of the racks respectively, the two lugs has a shaft hole respectively; a cam arranged between the two lugs, and the rotating shaft of the cam is through the shaft holes of the two lugs; the two opening plate parts of the U-shaped slice has a hole for containing the rotating shaft of the cam respectively; when the highest point of the cam deviate from the bottom of the groove of the U-shaped slice, the U-shaped slice is in the first position; when the highest point of the cam reach the bottom of the groove of the U-shaped slice, the U-shaped slice is in the second position; the two ends of the groove bottom mounted an extension spring to connect the guide box respectively.

The shaft of the said cam connected to a bar extending to radial direction, the terminal of the free end of the bar extending out of the shell of microwave oven. Moving the terminal of the free end of the bar can conveniently switch the automatic operation to manual operation or from the manual operation to the automatic operation.

Preferably, the said guide box divide into the upper and lower parts, a block slice mounted between the arc guide groove of the upper part and the arc guide groove of the lower part, this can prevent the interference between the racks when they are moving.

To let the door boards stop moving correctly, the said shell of the microwave oven has an opening limit switch and a closing limit switch; the opening limit switch will connect to one of the two connecting rods when the door opened totally; the closing limit switch will connect to the rod when the door closed totally; the opening limit switch, the closing limit switch and the said electric motor connected to control circuit board respectively.

According to one preferred embodiment of the present invention, all the driving components of the door boards arranged below the cavity; the V-shape hinged shaft of the two rods used as the rotating shaft of the tray of the microwave oven; the free ends of the two rods are fixed on the bottom edge of the door boards respectively.

Particularly, a driven component of the two door boards mounted upper the cavity; the free ends of the V-shape hinged shaft of the two rods mounted on the top side of the door boards respectively, and the V-shape hinged shaft of the two rods mounted on the gyration center of the door boards where is upper the cavity. This makes the opening and closing of the door boards more smoothly.

The opening mechanism of the cylindrical microwave oven of the present invention, by driving the two gears rotating reversely and synchronously via the electric motor, the gears will drive a rack, a rack-connected rod and a door to open or close respectively, thus perform the auto-opening and auto-closing of the door boards. The structure of the opening mechanism has not any moving blind-point, and can be smooth-moving and convenient-reversing, it is fit for the working character of the electric motor, and easy to switch the manual operation or auto operation. A driving gear mounted on the shaft of the electric motor and the rotating shafts of the two said gears mounted on a translation component, by the translation of the two gears to control the driving gear whether forms a driving relationship with the racks or not, to perform the switching between the auto operation and manual operation, and maintain the steady position of the racks and electric motor, high strength in the whole structure and high reliability. The translation component is a U-shaped slice which is easy to be manufactured and get high strength by selecting metal material. The U-shaped slice combined with the guide box mounted on the shell of the microwave oven; the guide box containing two racks and two gears, the driving gear of the electric motor mesh with a small gear coaxial with one of the two gears, this make the electric motor independent to the assembly structure of the guide box, thus easy to assembly and maintained. The switching from auto to manual via a cam can conveniently perform the switching between auto-opening and mechanical-opening in cleaning, and has a simply structure, good operation. The guide box dividing into upper and lower parts and setting a block slice can not only prevent the racks from interfering each other in moving, but also benefit to manufacture the guide box and assembly the racks and gears. The opening limit switch, the closing limit switch and the said electric motor connected to control circuit board respectively, one of the two rods connected to the opening limit switch or closing limit switch to control the electric motor to stop rotating, this operation is automatic and make the microwave oven smoothly in opening. When in closing if there are something blocked it will change to opening state to prevent from catching. The driving component arranged below the cavity is convenient to mount the microwave generator upper the cavity. The driven component mounted on the cavity can make the opening and closing of the door boards more smoothly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of the cylindrical microwave oven with the sectioned shell in one preferred embodiment of the present invention.

FIG. 2 is perspective view of the embodiment of FIG. 1 without the shell.

FIG. 3 is an exploded view of the door of the embodiment of FIG. 1.

FIG. 4 is a perspective view of the main structure of the opening mechanism of the cylindrical microwave oven in embodiment 2 of the present invention.

FIG. 5 is an explode view of the main body turned 180 degrees in embodiment 2 of FIG. 4.

FIG. 6 is an explode view of the main body turn 180 degrees assembled without the two rods in embodiment 2 of FIG. 4.

FIG. 7 is a perspective view of the main body turn 180 degrees without the two rods in embodiment 2 of FIG. 4.

FIG. 8 is a perspective view of the opening state of the cylindrical microwave oven without the shell in embodiment of FIG. 4.

FIG. 9 is a sectional view of the mounted component of the embodiment of FIG. 4 in the shell of the cylindrical microwave oven.

FIG. 10 is a perspective view of the closing state of the cylindrical microwave oven without the shell in embodiment of FIG. 4.

FIG. 11 is an explode view of the driven component of the door boards mounted upper the cavity of the cylindrical microwave oven in embodiment of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Embodiment 1

Referring to FIG. 1, it shows the structure of the cylindrical microwave oven in one preferred embodiment of the present invention. The cylindrical shell 1 with a window in the middle portion of the cylindrical microwave oven has a cylindrical cavity 2. There is a microwave generator 3 for radiating microwave to the cavity 2 mounted on the cavity 2 in the shell 1. A rotating tray 4 mounted in the cavity 2. An electric motor 5 for driving the rotating tray 4 mounted below the cavity 2 in the shell 1, the rotating shaft of the rotating tray 4 in cavity 2 is connected to the electric motor 5 through the bottom of cavity 2. The front window of the shell 1 has a circular arc door 6 for closing the cavity 2.

The shell 1 is a cylindrical bucket with an opening bottom and a window 101 in the middle portion. An upper slide way 11 for sliding and limiting for the door 6 mounted upper the window 101 in the shell 1, a bottom plate 12 mounted in the bottom of the shell 1, a lower slide way 121 for sliding and limiting for the door 6 mounted along the edge of the inside bottom plate.

Referring to FIG. 2, the cavity 2 comprises an upper disk cover 21, a U-shaped board 22 and a lower disk cover 23, the U-shaped board is supported between the upper cover and the lower cover to form a cylindrical cavity with a front opening. The side wall of the upper disk cover 21 extends downward, and the side wall of the lower disk cover 21 extends upward. Microwave generator 3 mounted in the upper side wall of the upper cover 21, the motor 5 mounted in the lower side wall of the lower cover 23, the rotating shaft of the motor 5 has a small gear 51, the small gear 51 meshes a big gear 42, this form a slow-down relationship; the rotating shaft 1 of the big gear 42 drives the shaft of the rotating tray 4 through the shaft hole 231 in the middle part of the lower cover 23.

The cavity door 6 which closing the opening front of the cavity can be divide into two door boards, everyone is a circular arc board; when the two door boards 6 opened, half of the inside space of cavity 2 are exposed, this is convenient for inputting or outputting foods. Referring to FIG. 3, an arc right-angle board 611 mounted on the top side of the left door board 61, each end of the top side of the board 611 mounted an extending upward pin 612. Each pin 612 mounted an upper pulley 613 which connect to the inside wall of the upper slide way 11. An arc right-angle board 621 mounted on the top side of the right door board 62, each end of the top side of the board 621 mounted an extending upward pin 622. Each pin 622 mounted an upper pulley 623 which connect to the inside wall of the upper slide way 11. The right end of the top side of the left door board 61 mounted a board 614, a vertical shaft 615 mounted on the board 614. The left end of the top side of the right door board 62 mounted a board 624, the board 624 mounted a vertical shaft 625, a hook 626 mounted on the vertical shaft 625. The right end of the bottom side of the left door board 61 mounted a board 617, a vertical shaft 618 mounted on the board 617, and a hook 619 mounted on the vertical shaft 618. The left end of the top side of the right door board 62 mounted a board 627, a vertical shaft 628 mounted on the board 627. When the door boards 61 and 62 closed, the hook 626 in the top side of the right door board 62 will catch the vertical shaft 615 in the top side of the left door board 61; the hook 619 in the bottom side of the left door board 61 will catch the vertical shaft 628 in the top side of the right door board 62; thus the door boards 61 and 62 will not be opened casually to prevent the microwave from leaking out so as to ensure the security. When being pressed larger pressure, the hook 626 on the top side will loose from the vertical shaft 615, the hook 619 on the bottom side will loose from the vertical shaft 628, thus the door boards are opened. The lower side of the left door board 61 mounted an arc right-angle board 71, each end of the bottom of the board 712 mounted a lower pulley 713 which connect to the inside wall of the lower slide way 121. The lower side of the right door board 62 mounted an arc right-angle board 72, each end of the bottom of the board 722 mounted a lower pulley 723 which connect to the inside wall of the lower slide way 121. The door boards 61 and 62 slide between the upper slide way 11 and lower slide way 121, the opening and closing will not occupy the outer space and be little-resistance and good-seal effect.

The bottom board 12 which supporting the cavity 2 mounted an opening mechanism 7 for the synchronous opening and closing of the door boards 61 and 62. The opening mechanism 7 comprises two long rods, two short rods and a guide board; the bottom side of the left door board 61 mounted a right-angle board 71, the middle of the bottom 712 of the board 71 extending inside a long rod 714, the bottom side of the right door board 62 mounted a right-angle board 72, the middle of the bottom 722 of the board 72 extending inside a long rod 724, the ends of the two rods 714 and 724 are V-shape hinged, the hinged shaft connected to the hole 772 in the back end of the guide board 77. The two short rods 73 and 74 are V-shape hinged, the bottom-end of their hinged shaft 79 connected slideably to the groove 771 in the front end of the guide board 77; the free end of the short rod 73 hinged to the middle portion of the long rod 714 via a stud pin 75, the free end of the short rod 74 hinged to the middle portion of the long rod 724 via a stud pin 76. The guide board 77 fixed on a bow guide board 78. The top of the bow guide board 78 has a groove 781 corresponding to the groove 771 in the front end of the guide board 77, and a shaft hole 782 corresponding to the shaft hole 772 in the back end of the guide board 77; the upper end of V-shape hinged shaft of the two short rods 73 and 74 connected slideably to the groove 781 in the front end of the guide board 78; the upper end of V-shape hinged shaft of the two long rods 714 and 724 hinged to the groove 782 in the back end of the guide board 78; the front and back ends of the guide board has a tenon respectively, which inserted in the mortise holes 783 and 784 in the front and rear side of the bow board 78 respectively. The front flat foot 785 of guide board 78 fixed on the front hole 123 of bottom board 12, the back flat foot 785 of guide board 78 fixed on the back hole 123 of bottom board 12. Between the front hole 123 and the back hole 124 there is a groove 125 corresponding to the guide groove 771 of the guide board 77 to prevent the bottom end of the hinged shaft of the two rods 714 and 724 from connecting to the bottom board 12. This mechanical can ensure the door boards 61 and 62 to open and close synchronously with the same degrees and with good seal effect.

Referring to FIG. 2, it shows the shape of the cavity 2, microwave generator 3, upper slide way 11, bottom board 12 and the two circular arc door boards 61 and 62 after assembled in this embodiment. When the door boards 61 and 62 being pressed by an outward pressure, the hook 626 on the top side will loose from the vertical shaft 615, the hook 619 on the bottom side will loose from the vertical shaft 628, thus the door boards 61 and 62 are opened, the cams 613 mounted on the topside of the door board 61 will roll along the inside wall of the upper slide way 11; the cams 623 mounted on the topside of the door board 62 will roll in opposite direction along the inside wall of the upper slide way 11; the lower cam 713 mounted on the bottom side of the door board 61 will roll along the inside wall of the lower slide way 121; the lower cam 723 mounted on the bottom side of the door board 62 will roll in opposite direction along the inside wall of the upper slide way 121; the door boards 61 and 62 slidely opened between the upper slide way 11 and lower slide way 121, simultaneously, the two long rods 714 and 724 are V-shape opened relative to their hinged shaft, this drive the two short rods 73 and 74 V-shape opened relative to their hinged shaft 79. The bottom end of the hinged shaft 79 of the short rods 73 and 74 slide backward along the groove 771 in the front of the guide board 77; the top end of the hinged shaft 79 of the short rods 73 and 74 slide backward along the groove 781 of the guide board 78, thus the door boards 61 and 62 opened backward synchronously and with the same degrees. The food can be put in or get out after the door boards 61 and 62 opened totally.

When the door boards 61 and 62 being pressed by the inward pressure, the cam 613 mounted on the topside of the door board 61 will roll along the inside wall of the upper slide way 11; the cam 623 mounted on the topside of the door board 62 will roll in opposite direction along the inside wall of the upper slide way 11; the cam 713 mounted on the bottom side of the door board 61 will roll along the inside wall of the lower slide way 121; the cam 723 mounted on the bottom side of the door board 62 will roll in opposite direction along the inside wall of the upper slide way 121; the door boards 61 and 62 slidely closed between the upper slide way 11 and lower slide way 121, simultaneously, the two long rods 714 and 724 are V-shape closed relative to their hinged shaft, this drive the two short rods 73 and 74 V-shape closed relative to their hinged shaft 79. The bottom end of the hinged shaft 79 of the short rods 73 and 74 slide frontward along the groove 771 in the front of the guide board 77; the top end of the hinged shaft 79 of the short rods 73 and 74 slide frontward along the groove 781 of the guide board 78, thus the door boards 61 and 62 closed frontward synchronously and with the same degrees. At last the hook 626 on the top side will lock with the vertical shaft 615, the hook 619 on the bottom side will lock with the vertical shaft 628, thus the door boards 61 and 62 are closed so as to begin to heat the food.

Certainly, anyone of the two long rods 714 and 724 can connect an arc rack, and use another motor to drive the arc rack via a driving gear to make the long rod swing relative to its hinged shaft, furthermore, on the combined effects of the short rods 73 and 74, the hinged shaft 79, groove 771 of the guide board 77, groove 781 of the guide board 78, another long rod will swing in opposite direction relative to it hinged shaft, thus perform the opening and closing. Or use another motor to drive the hinged shaft 79 of the two short rods 73 and 74 via a driving mechanism to move along the groove 771 of the guide board 77 and the groove 781 of the guide board 78, the short rods 73 and 74 V-shape opened or closed to drive the two long rods 714 and 724 V-shape opened or closed relative to their hinged shaft to perform the auto-opening or auto-closing.

Moreover, the microwave generator 3 can be mounted below the cavity 2 to let the microwave import into the cavity 2 from the side; and the opening mechanism 7 mounted on the cavity 2

Embodiment 2

A cylindrical microwave oven with two opposite-opening door boards inside the shell, herein the door boards can seal the front opening of the cylindrical cavity along the slide way. The opening mechanism of the cylindrical microwave oven mounted in the shell, which drives the door boards move to the opening or closing direction along the circle slide way; thus perform the auto-opening or auto-closing of the door boards along the circle slide way. The main body structure of the opening mechanism is showed in FIG. 4, more detailed description will be described in followings.

Referring to FIG. 5, the main body of the opening mechanism comprises the following parts: left rack 1′, right rack 2′, left rod 5′, right rod 6′, left gear 7′, right gear 8′, driving gear 9′, electric motor 10′, block slice 14′, upper guide box 15′, lower guide box 16′, cam 17′, cam shaft 18′, U-shaped slice 19′, two gear shafts 20′, two E-shape fasteners 21′, two extension springs 23′.

The left rack 1′ is a circular arc rack, its left end 101′ has bolt hole to connect the left rod 5′, its right end 102′ is a flat end without tooth, the inner side between the left end 101′ and right end 102′ is the teeth side 103′.

The right rack 2′ is a circular arc rack, its right end 201′ has bolt hole to connect the right rod 6′, its left end 202′ is a flat end without tooth, the inner side between the right end 201′ and left end 202′ is the teeth side 203′; There is an extending-out lug 204′ in the out side of the right end 201′.

The left rack 1′ has the same arc length, radius of curvature, tooth shape and tooth number as the right rack 2′.

The right end or the left rod 5′ has shaft hole 501′, the left end has a door-connecting part 502′, near the left end arranged the rack-connecting part 503′.

The left end or the right rod 6′ has shaft hole 601′, the right end has a door-connecting part 602′, near the right end arranged the rack-connecting part 603′.

The left rod 5′ and the right rod 6′ are symmetrical, they have the same length and the same distance from the shaft hole to the rack-connecting part.

The right gear 8′ combined by two coaxial gears: the big gear 801′ and the small gear 803′, herein the big gear 801′ has the same radius, tooth shape and tooth number as the left gear 7′.

Everyone of the four corners of the upper guide box 15′ has a bolt hole 1500′; the middle of the topside has an extending backward groove 1501′; In the front of the groove 1501′ there are two symmetrical long holes 1502′ in the left and right side respectively and an emboss strip 1503′ in the middle portion; the middle of the backside edge of the top of the upper guide box has a lug 1504′ extending backward, the lug 1504′ has a shaft hole 1505′. Referring to FIG. 6, the front of the bottom surface of the upper guide box 15′ has an arc groove 1506′, the backside wall of the groove 1506′ connected to a 8-shape groove 1507′ and three mounts 1508′, the front side wall of the groove 1506′ connected to two slots 1509′.

Everyone of the four corners of the lower guide box 16′ has a bolt hole 1600′; the front portion of the right side has a lug 1602′, the lug 1602′ extending to the bottom surface of the lower guide box 16′ to form a boss. The bottom surface near the right side of the lower guide box 16′ has a big round groove 1611′; and near the left side has a rib 1613′; the middle portion has a groove 1601′ extending backward. There are two symmetrical holes 1602′ in the left and right side respectively and an emboss strip 1603′ in the middle portion, the left part near the middle has a boss 1612′; the middle of the backside edge of the bottom side of the lower guide box 16′ has a lug 1604′ extending backward, the lug 1604′ has a shaft hole 1605′. The front side of the lower guide box 16+′ has a bolt hole 1614′ in the corresponding position to the rib 1613′ and has a bolt hole 1615′ in the corresponding position to the left side of the lug 1620′. Referring to FIG. 5, the front of the top surface of the upper guide box 16′ has an arc groove 1606′, the backside wall of the groove 1606′ connected to a groove 1607′; the bottom side of the groove 1607′ has a long, round small groove 1608′. The front wall of the groove 1608′ has a window 1609′ through which connected the big round groove 1611′ in the bottom surface. The back of the top surface of the lower guide box 16′ has a short vertical shaft 1610′ in each side of the lug 1604′ respectively.

The two plate parts of the U-shaped slice 19′ opened forward. Along the line of symmetry of the upper plate part 1901′ there is a long guide hole 1903′, both the front two sides of the hole 1903′ has a gear shaft hole 1902′ respectively; behind the long guide hole 1903′ there is a long, round cam shaft hole 1904′. The middle of groove bottom 1905′ of the U-shaped slice 19′ pressed forwardly a concave rib 1906′, each end of the groove bottom 1905′ has a hole 1907′, the lower plate part 1910′ of the U-shaped slice 19′ has a L-shaped opening 1913′ along the line of symmetry, each the front two sides of the opening 1913′ has a gear shaft hole 1912′ respectively; behind the long guide hole 1913′ there is a long, round cam shaft hole 1914′.

Referring to FIG. 6, let the top surface of the upper guide box 15′ towards down. The tooth surface 103′ of the left rack 1′ towards back, the right end 102′ put in the arc groove 1506′ of the upper guide box 15′. The left gear 7′ set in the deeper portion in the left side of groove 1507′; the right gear 8′ set in the shallow portion in the right side of groove 1507′, the lower part of the gear 801′ meshed the upper part of the gear 7′. The block slice 14′ covered the groove 1506′ of the upper guide box 15′, the two sticks 1401′ in the front of the block slice 14′ inserted in the two slots 1509′ of front side wall of the groove 1506′, the three claws 1402′ in the back of the block slice 14′ inserted in the three mounts 1508′ of the back side wall of the groove 1506′, thus the block slice 14′ fixed on the upper guide box 15′. The tooth-side 203′ of the right rack 2′ towards backwards, the left end 202′ set on the block slice 14′. Make the top surface of the lower guide box 16′ cover on the upper guide box 15′. The left end 202′ of the right rack 2′ get into the arc groove 1606′ of the lower guide box 16′; the big gear 801′ of the right gear 8′ get into the back groove 1607 of the groove 1606′, the small gear 803′ get into the small groove 1608′ in the bottom of the groove 1607′. Four bolts is through the bolt holes 1500 in the four corners of the upper guide box 16′ and the bolt holes 1600 in the four corners of the lower guide box 16′ respectively, and use four nuts to lock these four bolts to make the upper guide box joint with the lower guide box to form an approximate-rectangle guide box. Between the lug 1504′ of the upper guide box 15′ and the lug 1604′ of the lower guide box 16′ there set a cam 17′. The two plate parts of the U-shape slice 19′ inserted in the guide box, and the upper plate part 1901′ is in the groove 1501′ in the top surface of the upper guide box 15′, the long guide hole 1903′ of the upper plate part 1901′ ringed the embossed strip 1503′ of the upper guide box 15′, the lower plate part 1910′ of the U-shape slice 19′ is in the groove 1601′ in the bottom surface of the lower guide box 16′, the opening 1913′ of the lower plate part 1910′ stuck with the embossed strip 1603′ and the boss 1612′ of the lower guide box 16′. The two gear shafts 20′ inserted in the two gear shaft holes 1902′ in the upper plate part 1901′ of the U-shape slice 19′ respectively, the two gear shafts 20′ are through the two long holes 1502′ of the upper guide box 15′ respectively, then through the central hole 701′ of the left gear 7′ and the central hole 802′ of the right gear 8′, after through the two long holes 1602′ of the lower guide box 16′, the bottom ends of the two gear shafts 20′ are stuck out from the two gear shaft holes 1912′ in the lower plate part 1910′ of the U-shape slice 19′. The bottom ends of the two gear shafts 20′ are stuck by the two E-shape fasteners 21′ to let the two gear shafts 20′, left gear 7′ and right gear 8′ to joint with the U-shape slice 19′, the big gear 801′ of the right gear 8′ mesh with the left gear 7′ all along. The upper portion of the cam shaft 18′ is through the cam shaft hole 1914′ in the lower plate part 1910′ of the U-shape slice 19′, then through the shaft hole 1605′ of the lug 1604′ in the back of the lower guide box 16′, the shaft hole 1701′ of the cam 17′, the shaft hole 1505′ of the lug 1504′ in the back of the upper guide box 15′ in turn, at last through out from the hole 1904′ of the upper plate part of the U-shape slice 19′. A short pin 1801′ fit in holes in the cam 17′ and cam shaft 18′ to let the cam 17′ fixed on the upper part of the cam 18′. Two extension springs 23′ fixed in the holes 1907′ in the two terminals of the groove 1905′ of the U-shape slice 19′ and the two vertical shafts 1610′ in the two sides of the lugs 1604′ of the lower guide box 16′. The perspective view of the assembled components of the guide box is shown in the FIG. 7.

A driving gear 9′ mounted on the shaft 1002′ of the motor 10′. The driving gear 9′ fixed into the big round groove 1611′ of the lower guide box 16′, and one parts of the driving gear 9′ through over the window 1609′ to entry into the small groove 1608′. The two lugs 1001′ of the motor 10′ arranged in the lug 1620′ of the lower guide box 16′ and the bottom surface of the boss 1612′ respectively, the bottom surface of the lug 1620′ and the boss 1612′ has a location pin and a screw hole corresponding to the location hole and the screw hole in the lug 1001′, the two lugs 1001′ fixed on the lug 1620′ and the bottom surface of the emboss 1612′ by two bolts, then the motor 10′ is fixed on the guide box. After the left rod 5′ and right rod 6′ assembled, the perspective view of the main body structure of the opening mechanism is shown in FIG. 4.

Meanwhile, the highest point 1702′ of the cam 17′ deviated from the groove bottom 1905′ of the U-shape slice 19′, the U-shape slice 19′ drew forward by the force of the two intension springs 23′; The embossed strips 1503′ and 1603′ of the top and bottom surfaces of the guide box positioned in the back ends of the corresponding long guide holes 1903′ and 1913′ in the U-shape slice 19′, the left gear 7′ meshed the left rack 1′, the right gear 8′ meshed the right rack 2′, the driving gear 9′ of the motor 10′ meshed the small gear 803′ of the right gear 8′. The left rack 1′ and right rack 2′ are driven by motor 10′, the door boards connected with the left rod 5′ and the right rod 6′ are in the auto-operation state.

Rotate the cam shaft 18′ to let the cam 17′ push the groove bottom 1905′ of the U-shape slice 19′, the two extension springs stretched; until the groove way of the highest point 1702′ of the cam 17′ connected to the concave strip 1906′ of the groove bottom 1905′ of the U-shape slice 19′. The embossed strips 1503′ and 1603′ of the top and bottom surfaces of the guide box positioned in the front end of the corresponding long holes 1903′ and 1913′ in the U-shape slice 19′, the left gear 7′ deviate from the left rack 1′, the right gear 8′ deviate from the right rack 2′, the driving gear 9′ of the motor 10′ deviate from the small gear 803′ of the right gear 8′. The left rack 1′ and right rack 2′ can not driven by motor 10′, the door boards connected with the left rod 5′ and the right rod 6′ are in the manual-operation state.

As aforementioned, the right lug 1620′ of the lower guide box has a bolt hole 1614′, the left embossed strip 1613′ has a bolt hole 1615′, the main body of the opening mechanism can be assembled on the shell of the microwave oven via the two bolt holes.

Referring to FIG. 8, it shows the door-opening state of the cylindrical microwave oven without the shell. An upper disk cover 40′, a U-shaped board 90′ and a lower disk cover 60′ formed the cavity in the shell of the microwave oven. The U-shaped board 90′ supported between the upper cover 40′ and lower cover 60′ to form a cylindrical cavity with an opening front. The opposite-opened left door 3′ and right door 4′ mounted close to the round slide ways in the peripheral region of the upper cover 40′ and lower cover 60′ in the two sides of the opening front of the cavity. And also referring to FIG. 9, the shaft 71′ of the tray 70′ in the centre of the lower cover 60′ is through the shaft hole 501′ of the right end of the left rod 5′ and the shaft hole 601′ of the left end of the right rod 6′. The door-connecting part 502′ of the left end of the left rod 5′ fixed in the bottom side of the left door 3′. The rack-connecting part 503′ of the left rod 5′ is fixed-joint with the left end 101′ of the left rack 1′. The door-connecting part 602′ of the right end of the right rod 6′ fixed in the bottom side of the right door 4′. The rack-connecting part 603′ of the right rod 6′ is fixed-joint with the right end 201′ of the right rack 2′. Thus the rods 5′ and 6′ V-shape hinged to the shaft 71′ of the tray 70′ in the rotating center of the door 3′ and 4′; the two arc racks 1′ and 2′ are up-down staggered and fan out in one concentric circle of the said gyration center.

A bracket 51′ mounted between the under-pan 50′ and the lower cover 60′. The bracket 51′ has an opening-limit switch 12′, closing-limit switch 13′ and circuit board 11′; the opening-limit switch 12′, closing-limit switch 13′, motor 10′ connected to the circuit board 11′ respectively. This art is well known in the field and not detailed described here.

Referring to FIG. 8, when the left door 3′, the right door 4′ are opened totally, the flexible slice of the opening-limit switch 12′ contacted to the lug 204′ of the right end 201′ of the right rack 2′ in the rack-connecting part 603′ of the right rod 6′. While the left door 3′ and the right door 4′ are closing, the right rod 6′ and the right rack 2′ contracted leftward; When the left door 3′ and the right door 4′ are closed totally, the flexible slice of the closing-limit switch 13′ contacted to the lug 204′ of the right end 201′ of the right rack 2′ in the rack-connecting part 603′ of the right rod 6′.

When the left door 3′ and the right door 4′ are closed, the structure of the cylindrical microwave oven without the shell in this embodiment is shown in the FIG. 10, an elongated window 52′ of the bracket 51′ stick out a selector rod 22′, the root of the selector rod 22′ fixed on the cam shaft 18′ by a short pin 1802, while its body extending to the radial direction. The free end of the selector rod 22′ sticks out the shell from the microwave oven. The action of the selector rod 22′ is to rotate the cam shaft 18′ to perform the switching between the manual operation and the automatic operation. The cover 40′ mounted the driven components of the door boards 3′ and 4′ in this embodiment to let the opening and closing of the door boards 3′ and 4′ more smoothly.

Referring to FIG. 11, the driven component comprises: a beam 30′, a shaft 31′, two supporting brackets 32′, a U-shape bracket 33′, a left rod 15′, a right rod 36′. The rods 35′ and 36′ V-shape hinged to the shaft 31′, the bottom end of the shaft 31′ inserted in the centre hole of the U-shape bracket 33, the U-shape bracket 33 arranged below the middle of the beam 30′ to let the upper end of the shaft 31′ insert in the shaft hole 301′ in the middle of the beam 30′. the two supporting brackets 32′ rest on the two sides of the top surface of the upper cover 40′ symmetrically, the two ends of the beam 30′ fixed on the two supporting brackets 32′ respectively, the shaft 31′ V-shape hinged by the rods 35′ and 36′ positioned on the middle of the beam 30′ on the cavity, i.e. the rotating-centre position of the door boards 3′ and 4′. The free ends of the V-shape hinged rods 35′ and 36′ fixed on the top side of the left door boards 3′ and 4′.

In other apply situation, if the microwave generator mounted below the cavity, and let the microwave radiate into the cavity from the side, then the opening mechanism of the present invention can be mounted on the cavity.

The cavity of the cylindrical microwave oven of the present invention is cylindrical, and the radius of gyration of the rotating tray is used as the cylinder diameter, thus it is not only making the best of the space, but also benefit to the radiating distribute of the microwave, which save the heating time of the microwave acting on the food and improve the efficiency. It use the opposite-opened circular arc door boards, after opened, the door boards opened at the opposite forward at the same time and sliding on the circle slide way, this save the outer space needed in the hinged opening door boards. When the door boards opened, half of the cavity will be exposed, which is convenient to input and output of the vessel and to clean the cavity. The opening mechanism is a four-link structure having two opposite-opened V-shape, this can ensure the synchronous opening, same opening degrees and good seal effect of the two door boards. The opening mechanism of the cylindrical microwave oven of the present invention, by driving the two gears rotating reversely and synchronously via the electric motor, the gears will drive a rack, a rack-connected rod and a door to open or close respectively, thus perform the auto-opening and auto-closing of the door boards. the structure of the opening mechanism has not any moving blind-point, and can be smooth-moving and convenient-reversing, it is fit for the working character of the electric motor, and easy to switch the manual operation or auto operation.

The foregoing description of the exemplary embodiment of the invention has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Many modifications and variations are possible in light of the above teaching. It is intended that the scope of the invention be limited not with detailed description, but rather by the claims appended hereto. 

1. A cylindrical microwave oven comprising a shell and an oven cavity and a microwave generator radiating microwave into the cavity inside the shell; a door for closing or opening the cavity is mounted in the front of the shell; wherein an upper disk cover, a U-shaped board and a lower disk cover form a cavity with a front opening; the U-shaped board is supported between the upper cover and the lower cover; and the door is a circular arc board for closing or opening the front opening of the cavity.
 2. The cylindrical microwave oven according to claim 1, wherein the door comprises two door boards openable in opposite direction, and an opening mechanism for controlling the opening and closing of the two door boards mounted on the shell.
 3. The cylindrical microwave oven according to claim 2, wherein the opening mechanism comprises two long rods, two short rods and a guide board; the two long rods are V-shape hinged and their hinged axis is hinged to one terminal of the guide plate; the free ends of the two long rods are fixed on the lower portion of the two oven door boards respectively; the two short rods are V-shape hinged and their hinged axis is connected slideably to the other terminal of the guide board; the free ends of the two short rods are hinged to the middle portion of the two long rods respectively; and the guide board fixed on the shell.
 4. The cylindrical microwave oven according to claim 2, wherein the butt sides of the two door boards are mounted via hook mechanisms.
 5. The cylindrical microwave oven according to claim 1, wherein the opening mechanism of the cylindrical microwave oven is that the two door boards opposite-opened along the slide way inside the shell of the microwave oven can seal the front opening of the cylindrical cavity, the gyration center of the door boards has a rotating shaft which V-shaped hinged with two rods; the free ends of the two rods fixed on the same side door boards respectively; one concentric circle of the said gyration center arranged two up-down staggered and fan out circular arc racks, each fan out terminals of the two said racks connected to a said rod respectively; each side of the symmetric line of the fan out racks mounted a gear respectively, the said gears mesh each other and each mesh to one rack respectively, one of the gears connected to the electric motor.
 6. The cylindrical microwave oven according to claim 1, wherein the opening mechanism, a driving gear mounted on the rotating shaft of the electric motor; the rotating shafts of the two gears mounted on a translation component; when the translation component is on the first position, the driving gear will mesh the first gear; when the translation component moved to the second position, the driving gear will deviate from the first gear.
 7. The cylindrical microwave oven according to claim 6, wherein the translation component is a U-shaped slice mounted on the tooth side of the two racks, both the two opening plate parts of the U-shaped slice has two holes for mounting the rotating shaft of the two gears respectively; when the U-shaped slice is on the first position, the two gears will mesh their corresponding rack and the driving gear mesh the first gear; when the U-shaped slice is on the second position where is far from the tooth side of the two racks, the two gears will deviate from their corresponding rack and the driving gear deviate from the first gear.
 8. The cylindrical microwave oven according to claim 7, wherein the said U-shaped slice inserted in a guide box on the shell of the microwave oven; the two plate parts of the U-shaped slice has a long guide hole respectively, the upper and lower surfaces of the guide box has a embossed strip inserted in the corresponding long guide hole of the U-shaped slice respectively; the guide box has an upper and a lower staggered arc grooves for containing the two racks, the two said gears are mounted in the rack guide box respectively, herein the first gear has a coaxial smaller gear; when the U-shaped slice is on the first position, the embossed strips of the top and bottom surfaces of the guide box will be in the terminal having corresponding long guide hole of the U-shaped slice, the two gears will mesh their corresponding racks and the driving gear of the electric motor will mesh the small gear of the first gear; When the U-shaped slice is on the second position, the embossed strips of the top and bottom surfaces of the guide box will be in the other terminal having corresponding long guide hole of the U-shaped slice, the two gears will deviate from their corresponding racks and the driving gear of the electric motor will deviate from the small gear of the first gear.
 9. The cylindrical microwave oven according to claim 7, wherein the top and bottom surfaces of the said guide box has a lug extending out from the tooth side of the racks respectively, the two lugs have a shaft hole respectively; a cam arranged between the two lugs, and the rotating shaft of the cam is through the shaft holes of the two lugs; the two opening plate parts of the U-shaped slice has a hole for containing the rotating shaft of the cam respectively; when the highest point of the cam deviates from the bottom of the groove of the U-shaped slice, the U-shaped slice is in the first position; when the highest point of the cam reaches the bottom of the groove of the U-shaped slice, the U-shaped slice is in the second position; the two ends of the groove bottom mounted an extension spring to connect the guide box respectively.
 10. The cylindrical microwave oven according to claim 9, wherein the shaft of the cam connected to a bar extending to radial direction, the terminal of the free end of the bar extending out of the shell of the microwave oven.
 11. The cylindrical microwave oven according to claim 9, wherein the guide box divides into the upper and lower parts, a block slice mounted between the arc guide groove of the upper part and the arc guide groove of the lower part.
 12. The cylindrical microwave oven according to claim 11, wherein the shell of the microwave oven has an opening limit switch and a closing limit switch; the opening limit switch connects to one of the two connecting rods when the door opened totally; the closing limit switch connects to the rod when the door boards closed totally; the opening limit switch, the closing limit switch and the said electric motor connected to control circuit board respectively.
 13. The cylindrical microwave oven according to claim 12, wherein the V-shape hinged shaft of the two rods used as the rotating shaft of the tray of the microwave oven; the free ends of the two rods are fixed on the bottom edge of door boards respectively.
 14. The cylindrical microwave oven according to claim 12, wherein the free ends of the V-shape hinged shaft of the two rods mounted on the top side of the door boards respectively, and the V-shape hinged shaft of the two rods mounted on the gyration center of the door boards where is upper the cavity. 